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Topic Review (Newest First)

11-29-2007 06:17 PM

techron

OK, you say that you mocked up the rear end without the engine/trans in and you can deflect the C beam (thats the beam that runs foreward and bolts to the trans at the front) up/down 30 degrees, it will move up and down because the trans is not there. to get what i am saying put a jackstand under the front of the beam to simulate the trans mount, with the front of the beam on the jackstand see how far you can push the beam down, heck, jump on it if you want.

what you want to do is mount the rear end (i assume already done), next mock up the engine + trans in the car so it is pointing directly at the pinion (and the pinion is pointing directly at the trans output shaft). you need to get everything-pinion, trans output on the same plane- so that when the driveshaft is in you have 0 deflection on both u-joints, like this =-=. this needs to be done first. only when you have your engine, trans and rearend mounts made and everything is lined up you can start to build your new shorter C beam out of steel tubing.

i know you are concerned about how short your driveshaft will be but with what little deflection rubber bushings will give the u joints will easily handle. just get everything mounted and lined up before making your new C beam.

11-29-2007 09:01 AM

fustkarr

hadda find this in the manual

Page 3D-1, Chevrolet Factory Shop Manual {1984),published by Helm,Inc.;Quote:Each wheel is mounted by a five link independent suspension.The five links are identified as the wheel driveshaft,camber control suppost rod, upper and lower control arms and tie rod.:Unquote.
My bad, i haddn't read the manual in months and was under the impression that the drive line support/beam was the 5th link.
I am assuming that the support beam cushions the shock of hard accelleration, putting a little "fudge factor" into getting the car rolling or into another gear w/o a lot of tire spin.I'll be doing extensive modifications to the frame and engine location {going to a five speed from a auto} and would like to provide for controlling the pinion wrap-up, should the results{of the frame mods} prove to be less than ideal, thus the question about the shock/pinion snubber. I'm concerned about constricting the movement of the pinion or possible shortening the life of the d-shaft, and would like to provide for the possibility of dealing with the problem should it appear.I've dry run the beam w/o engine trans in the frame and it moves {with only arm power} at least 30 degrees{not counting pinion travel upon downshift}. My impressions are: the beam will defect somewhat just because of its lenght/material and it is mounted in rubber "gaskets" {providing "give"}. So when i build another beam to replace the existing one , it will be shorter{stiffer} and probably made outta 3/4-1" square tubing{stiffer}. will this cause a problem with trans/motor movement or possibly negate the effect of the trans/rear-end connection?Just how critical is the effect of the beam?I'm assuming the increased weight of the engine/trans proximity will make the pinion wind-up even more markedly.
Anyway, the plan rt now is to include some sort of pinion control device and build a trans crossmember w/a stock trans. rubber bumper.
Any/all imput appreciated, Randy

11-28-2007 07:20 PM

techron

Quote:

Originally Posted by adtkart

I don't believe I have seen that type of mount. The ones I was thinking about were the ones with a large flat on the rear cover. Was actually thinking about seeing if that cover would fit on my housing. Then I would have to re-engineer the tie-rod (don't know the correct name) for the toe settings, since it is attached to the original cover. I don't like the way the "batwing" looks from the rear under a Model T.

Aaron

aaron, not a real clear picture but of you look at the first pic you can see the U shaped bracket under and foreward of the spring where it bolts to centersection and runs foreward to the frame. that rubber hockeypuck bushing sit between the bracket and frame it's the same from 63-82. you can also see the crossmsmber that holds the rear and bolts to the frame, there is a rubber coffeecup isolater between the frame and crossmember on each end.

I don't believe I have seen that type of mount. The ones I was thinking about were the ones with a large flat on the rear cover. Was actually thinking about seeing if that cover would fit on my housing. Then I would have to re-engineer the tie-rod (don't know the correct name) for the toe settings, since it is attached to the original cover. I don't like the way the "batwing" looks from the rear under a Model T.

Aaron

11-27-2007 07:48 PM

techron

Quote:

Originally Posted by adtkart

Techron.... You are right of course, in that it does not move with the suspension. Being mounted thru rubber bushings does not make it very rigid by any standards I know of. Without that connection to the trans, the pinion angle can change by probably 25 deg or more on that model. Some of the other years had plates that bolted directly to the frame. That was rigid.

Aaron

i agree, without the connection to the trans it would probably twist right off, i think 25 deg would be a conservative estamate. i'm doing a 64 now and the third member has a bracket that bolts to the housing directly under the pinion but bolts to the frame with rubber hockey puck bushings above and below the frame bracket so they are not really rigid either.

11-27-2007 04:59 PM

adtkart

Techron.... You are right of course, in that it does not move with the suspension. Being mounted thru rubber bushings does not make it very rigid by any standards I know of. Without that connection to the trans, the pinion angle can change by probably 25 deg or more on that model. Some of the other years had plates that bolted directly to the frame. That was rigid.

Aaron

11-26-2007 08:12 PM

techron

Quote:

Originally Posted by adtkart

I have an 84 Chevette rear suspension that I am installing in a Model T. The 3rd member does not fasten solid to the frame. It has a wing that goes from side to side for location. There is a "C" member that is supposed to connect to the transmission that keeps the 3rd member in the correct position, keeping it from rotating up or down.

Aaron

no offence Aaron, clarefication-notorious said "mounted rigid.....for all practical purposes" the wing you refered to is called the "batwing" and has bushings where it bolts to the frame but i would say it is rigid for all PRACTICAL PURPOSES (does not move with suspension)

to the OP-- the C beam is the peice running foreward to the trans. i would just fab a new, shorter C beam out of steel to match the new shorter distance. forget the shock or anything else to control third member rotation, you want it "rigid" pointing straight at the trans, thats what the C beam is for. don't try to outengineer chevy, just make a shorter C beam that serves the same purpose.

11-26-2007 07:39 PM

adtkart

I have an 84 Chevette rear suspension that I am installing in a Model T. The 3rd member does not fasten solid to the frame. It has a wing that goes from side to side for location. There is a "C" member that is supposed to connect to the transmission that keeps the 3rd member in the correct position, keeping it from rotating up or down.

Aaron

11-25-2007 06:54 PM

Notorious

I'm trying to understand how you consider this a 5 link system. It has four forward links that GM calls "control arms" and two lower control arms that are known as "camber arms" or "camber rods." I'm not sure what you're talking about about when referring to a dampening device on the 3rd member as it's mounted rigid in the Corvette, for all practical purposes. The front of the 3rd member is bolted to a C beam which goes forward and is bolted to the transmission's tailshaft. It seems you're equating this to a live axle in a dirt car. It shares no characteristics with that system since the differential is mounted to the chassis and doesn't move during suspension travel.

11-25-2007 06:25 PM

Deuce

As the Moderator in both of the forums you posted the two above questions in ... I merged the two post together and have made this post to bring your question back to the top in hopes of a answer ..

Deuce ... Moderator

11-21-2007 09:41 AM

fustkarr

vette/5th link......sumtins gotta give

Ok, i posted this last nite b4 work but i guess i didn't do it rt. Here's the problem: i'm using a '84 vette frame/suspension on a project and i'm moving the engine/trans back about 2 feet, the result is a 6" d-shaft and i've probably completly disabled the 5th link. However, in the past i've seen a device that attaches to the r/e imput snout and resembles a coilover and is used to control the movement of said r/e. This was on a dirt car so the next search will be the local newsstand for a Circle Track etc. rag. Does anyone have experience w/this device or a way to control the wind-up of the r/e?
Any/all imput appreciated, Randy

11-20-2007 10:39 PM

fustkarr

5 link vette suspension

I'm in the process of installing a vette frame/rear-end into a projectcar. The motor/trans is being pushed back to the point of having a 6" long drive shaft so the 5Th link {r/e to trans} effectiveness has become questionable. I'm now thinking about adding trans mounts rather than using the 5th link that come stock w/the vette {1984}. The question is: I've seen r/e imput snout wind-up control "shocks" b4 {on dirt cars}, these look like they will work to replace the stock 5th link ,so does anyone have experience with this set-up, a manufacturer,a link to a dirt car/vette roadracer who is familiar w/this set-up or another cure?
Any/all imput appreciated,Randy